JP6305479B2 - Electrochemical cell - Google Patents

Description

  The present invention relates to an electrochemical cell.

  Conventionally, as a kind of electrochemical cell, an insulating porous support substrate, a plurality of first power generation units disposed on the first main surface of the porous support substrate, and a second main surface of the porous support substrate are disposed. There is known a fuel cell including a plurality of second power generation units and an insulating dense seal layer covering an outer surface of a porous support substrate (see, for example, Patent Document 1). The dense seal layer described in Patent Document 1 is made of the same material (for example, YSZ (yttria stabilized zirconia)) as the electrolyte layer of the power generation unit.

Japanese Patent Laying-Open No. 2015-164094

  However, since the dense seal layer described in Patent Document 1 can flow negatively charged oxide ions, a weak leak current may flow from the first power generation unit to the second power generation unit.

  This invention is made | formed in view of the above-mentioned situation, and is providing the electrochemical cell which can suppress an internal leakage current.

  The electrochemical cell according to the present invention includes an insulating porous support substrate having a first main surface, a second main surface, a first side surface, and a second side surface, and a first main surface disposed on the first main surface of the porous support substrate. A power generation unit, a second power generation unit disposed on the second main surface of the porous support substrate, and a dense seal layer covering the porous support substrate are provided. The dense seal layer includes a first seal portion that covers the first main surface and a second seal portion that covers at least a part of the first side surface and continues to the first seal portion. The electrical resistivity of the second seal part is higher than the electrical resistivity of the first seal part.

  ADVANTAGE OF THE INVENTION According to this invention, the electrochemical cell which can suppress an internal leak current can be provided.

A perspective view of a fuel cell according to an embodiment A perspective view of a fuel cell according to an embodiment Sectional drawing in the cut surface A of FIG. BB sectional view of FIG.

(Configuration of fuel cell 1)
The configuration of the fuel cell 1 according to the present embodiment will be described with reference to the drawings. FIG. 1 is a perspective view of the fuel cell 1 as viewed from the first main surface S1 side of the porous support substrate 2. FIG. FIG. 2 is a perspective view of the fuel cell 1 as viewed from the second main surface S2 side of the porous support substrate 2. FIG.

  The fuel cell 1 is a so-called horizontal stripe type solid oxide fuel cell (SOFC: Solid Oxide Fuel Cell). The fuel cell 1 includes a porous support substrate 2, six power generation units 10, front and back connection units 20, and a dense seal layer 30.

(1) Porous support substrate 2
The porous support substrate 2 is formed in a flat plate shape extending in the longitudinal direction. The porous support substrate 2 has a first main surface S1, a second main surface S2, a first side surface S3, and a second side surface S4. Each of the first main surface S1 and the second main surface S2 is a plate surface extending in the longitudinal direction and the short direction of the porous support substrate 2. The short side direction is a direction perpendicular to the long side direction. The first main surface S1 is provided on the opposite side of the second main surface S2. Each of the first side surface S3 and the second side surface S4 is continuous with the first main surface S1 and the second main surface S2. The first side surface S3 is provided on the opposite side of the second side surface S4. In the present embodiment, each of the first side surface S3 and the second side surface S4 is formed in a curved curved surface shape, but may be formed in a planar shape.

  The porous support substrate 2 may be porous as long as the porosity is not particularly limited, but may be 25% to 50%. Although the thickness in the thickness direction of the porous support substrate 2 is not particularly limited, it can be 1 mm to 10 mm. The thickness direction is a direction perpendicular to the longitudinal direction and the short direction.

  Six gas flow paths 2 a are formed inside the porous support substrate 2. Each gas flow path 2 a extends along the longitudinal direction of the porous support substrate 2. In the present embodiment, fuel gas is caused to flow through each gas flow path 2a during power generation. The number of gas flow paths 2a is not limited to six.

The porous support substrate 2 is made of an insulating porous material that does not have electronic conductivity. The porous support substrate 2 includes, for example, CSZ (calcia stabilized zirconia), a composite material of MgO (nickel oxide) and YSZ (yttria stabilized zirconia), a composite material of MgO (nickel oxide) and Y ₂ O ₃ (yttria), A composite material of MgO (magnesium oxide) and MgAl ₂ O ₄ (magnesia alumina spinel) can be used. The porosity of the porous support substrate 2 can be 20% or more and 60% or less.

(2) Power generation unit 10
The six power generation units 10 include three first power generation units 10a disposed on the first main surface S1 of the porous support substrate 2 and three second power generation units disposed on the second main surface S2 of the porous support substrate 2. 10b.

  The three first power generation units 10 a are arranged in the longitudinal direction of the porous support substrate 2. The three second power generation units 10 b are arranged in the longitudinal direction of the porous support substrate 2. The first power generation unit 10a and the second power generation unit 10b have the same configuration. In the following description, the first power generation unit 10a and the second power generation unit 10b may be collectively referred to as the power generation unit 10.

  Here, FIG. 3 is a cross-sectional view taken along section A of FIG. The cut surface A is a plane perpendicular to the short direction. As shown in FIG. 3, each power generation unit 10 includes a fuel electrode 4, a solid electrolyte layer 5, an air electrode 6, an air electrode current collecting layer 7, and an interconnector 8.

  The fuel electrode 4 is disposed on the porous support substrate 2. The fuel electrode 4 functions as an anode. The anode 4 has an anode current collecting layer 41 and an anode active layer 42.

The anode current collecting layer 41 is disposed on the porous support substrate 2. The anode current collecting layer 41 is made of a material containing NiO and having electron conductivity. The anode current collecting layer 41 may contain a substance having oxygen ion conductivity. The anode current collecting layer 41 can be made of, for example, NiO-8YSZ, NiO—Y ₂ O ₃ , NiO—CSZ, or the like. The thickness of the anode current collecting layer 41 is not particularly limited, but can be 50 μm to 500 μm. The anode current collecting layer 41 may be porous, and the porosity is not particularly limited, but may be 25% to 50%.

  The anode active layer 42 is disposed on the anode current collecting layer 41. The anode active layer 42 is composed of a substance having electron conductivity and a substance having oxygen ion conductivity. The anode active layer 42 can be made of, for example, NiO-8YSZ, NiO-GDC (gadolinium-doped ceria), or the like. The volume ratio of the substance having oxygen ion conductivity in the anode active layer 42 is preferably larger than the volume ratio of the substance having oxygen ion conductivity in the anode current collecting layer 41. The thickness of the anode active layer 42 is not particularly limited, but can be 5 μm to 30 μm. The porosity of the anode active layer 42 is not particularly limited, but can be 25% to 50%.

The solid electrolyte layer 5 is disposed on the fuel electrode 4. The solid electrolyte layer 5 extends in the longitudinal direction from one interconnector 8 to another interconnector 8. Therefore, the solid electrolyte layers 5 and the interconnectors 8 are alternately arranged in the longitudinal direction of the fuel cell 10. The solid electrolyte layer 5 functions as a gas barrier layer that prevents mixing of the fuel gas on the porous support substrate 2 side and the air on the air electrode 6 side .

  The solid electrolyte layer 5 is made of a dense material having oxide ion conductivity higher than electron conductivity. The solid electrolyte layer 5 can contain zirconia as a main component. As a material constituting the solid electrolyte layer 5, for example, 3YSZ, 8YSZ, ScSZ, or the like can be used. The porosity of the solid electrolyte layer 5 is lower than the porosity of the porous support substrate 2 and the fuel electrode 4. The porosity of the solid electrolyte layer 5 can be 20% or less, and is preferably 10% or less. The thickness of the solid electrolyte layer 5 is not particularly limited, but can be 3 μm to 50 μm.

The air electrode 6 is disposed on the solid electrolyte layer 5. The air electrode 6 is made of a porous material having mixed conductivity. Examples of the material constituting the air electrode 6 include (La, Sr) (Co, Fe) O ₃ (LSCF, lanthanum strontium cobalt ferrite), (La, Sr) FeO ₃ (LSF, lanthanum strontium ferrite), La ( Ni, Fe) O ₃ (LNF, lanthanum nickel ferrite), (La, Sr) CoO ₃ (LSC, lanthanum strontium cobaltite), and the like. The thickness of the air electrode 6 is not particularly limited, but can be 10 to 100 μm.

  The air electrode current collecting layer 7 is disposed on the air electrode 6. The air electrode current collecting layer 7 is made of a porous material having electron conductivity. The air electrode current collecting layer 7 can be made of, for example, LSCF, LSC, Ag (silver), Ag—Pd (silver palladium alloy), or the like. The thickness of the air electrode current collecting layer 7 is not particularly limited, but may be 50 μm to 500 μm.

The interconnector 8 is made of a dense material having electronic conductivity. The interconnector 8 can be made of, for example, LaCrO ₃ (lanthanum chromite) or (Sr, La) TiO ₃ (strontium titanate). The porosity of the interconnector 8 is preferably less than 20%, more preferably 10% or less, and even more preferably 8% or less. The interconnector 8 along with the solid electrolyte layer 5 functions as a gas barrier layer that prevents mixing of the fuel gas on the porous support substrate 2 side and the air on the air electrode 6 side. The thickness of the interconnector 8 can be set to 10 to 100 μm, for example.

  (3) Front-back connection part 20 The front-back connection part 20 is provided in the one end part of the porous support substrate 2, as shown in FIG.1 and FIG.2. The front / back connection part 20 is wound around one end of the porous support substrate 2.

  As shown in FIG. 3, the front and back connection portion 20 includes the interconnector 8 of the first power generation unit 10a on the first main surface S1 side and the air electrode current collecting layer 7 of the second power generation unit 10b on the second main surface S2 side. And connected to. In the present embodiment, the front / back connection part 20 is formed integrally with the air electrode current collecting layer 7 of the second power generation part 10b.

The front / back connection part 20 can be made of a conductive ceramic material. As the material constituting the front and back connection part 20, (La, Sr) (Co, Fe) O ₃ (LSCF; lanthanum strontium cobalt ferrite), (La, Sr) CoO ₃ (LSC; lanthanum strontium cobaltite), La ( Ni, Fe, Cu) O ₃ or a composite material including at least two of them can be used.

  The porosity of the front / back connection part 20 is not particularly limited, but may be, for example, 25% to 50%. Although the thickness in particular of the front-and-back connection part 20 is not restrict | limited, It can be set as 50 micrometers-500 micrometers.

(4) Dense seal layer 30
The dense seal layer 30 covers the outer surface of the porous support substrate 2. The dense seal layer 30 is formed so as to be continuous with the solid electrolyte layer 5 of the power generation unit 10. In the present embodiment, the dense seal layer 30 functions as a gas barrier layer together with the solid electrolyte layer 5 and the interconnector 8.

  Here, FIG. 4 is a BB cross-sectional view of FIG. The dense seal layer 30 includes a first seal portion 31, a second seal portion 32, a third seal portion 33, and a fourth seal portion 34.

  The first seal portion 31 covers the first main surface S <b> 1 of the outer surface of the porous support substrate 2. The 1st seal | sticker part 31 has covered the area | region other than the area | region where the three 1st electric power generation parts 10a are arrange | positioned among 1st main surface S1 entirely. In this embodiment, the 1st seal | sticker part 31 is integrally formed with the solid electrolyte layer 5 of each of the three 1st electric power generation parts 10a. That is, the 1st seal | sticker part 31 is comprised by extending each solid electrolyte layer 5 outside.

  The first seal portion 31 is made of a dense material having a lower electrical resistivity than the second seal portion 32 and the fourth seal portion 34. The 1st seal | sticker part 31 can be comprised with the material used for the solid electrolyte layer 5, ie, 3YSZ, 8YSZ, ScSZ, etc. The electrical resistivity of the first seal portion 31 is not particularly limited, but can be 1 [Ωcm] or more and 10000 [Ωcm] or less. In the present embodiment, the electrical resistivity is a well-known DC four in an atmospheric environment at a general power generation temperature (600 ° C. to 1000 ° C.) of a solid oxide fuel cell or in a fuel gas atmosphere supplied to the fuel electrode 4. It is a value measured by the terminal method.

  The second seal portion 32 covers the first side surface S <b> 3 of the outer surface of the porous support substrate 2. The second seal portion 32 extends along the longitudinal direction of the porous support substrate 2. In the present embodiment, the second seal portion 32 entirely covers the first side surface S3. The second seal portion 32 continues to one end of each of the first seal portion 31 and the third seal portion 33 in the short direction of the porous support substrate 2. In the present embodiment, the second seal portion 32 is formed in a curved shape along the first side surface S3 of the porous support substrate 2, but when the first side surface S3 is formed in a planar shape, The two seal portions 32 are also formed in a planar shape.

The second seal portion 32 is made of a dense material having a higher electrical resistivity than the first seal portion 31 and the third seal portion 33. The second seal portion 32 is, for example, crystallized glass, spinel oxides, MgO (magnesia), _Al 2 _{O 3 (alumina) may} be constituted by at least one selected from Y 2 _{O 3} (yttria) . The electrical resistivity of the second seal portion 32 is not particularly limited, but can be 10000 [Ωcm] or more and 1 × 10 ¹² [Ωcm] or less, preferably 1 × 10 ⁵ [Ωcm] or more. × 10 ⁶ [Ωcm] or more is more preferable.

  The third seal portion 33 is provided on the opposite side of the first seal portion 31 across the porous support substrate 2. The third seal portion 33 covers the second main surface S <b> 2 of the outer surface of the porous support substrate 2. The third seal portion 33 entirely covers a region of the second main surface S2 other than the region where the three second power generation units 10b are disposed. In the present embodiment, the third seal portion 33 is formed integrally with the solid electrolyte layer 5 of each of the three second power generation portions 10b. That is, the third seal portion 33 is configured by extending each solid electrolyte layer 5 outward.

  Similar to the first seal portion 31, the third seal portion 33 is made of a dense material having a lower electrical resistivity than the second seal portion 32 and the fourth seal portion 34. The third seal portion 33 can be made of a material used for the solid electrolyte layer 5, that is, 3YSZ, 8YSZ, ScSZ, or the like. The electrical resistivity of the third seal portion 33 is not particularly limited, and can be set to 1 [Ωcm] or more and 10000 [Ωcm] or less similarly to the first seal portion 31.

  The fourth seal portion 34 is provided on the opposite side of the second seal portion 32 across the porous support substrate 2. The fourth seal portion 34 covers the second side surface S <b> 4 of the outer surface of the porous support substrate 2. The fourth seal portion 34 extends along the longitudinal direction of the porous support substrate 2. In the present embodiment, the fourth seal portion 34 entirely covers the second side surface S4. The fourth seal portion 34 continues to the other end of each of the first seal portion 31 and the third seal portion 33 in the short direction of the porous support substrate 2. In the present embodiment, the fourth seal portion 34 is formed in a curved shape along the second side surface S4 of the porous support substrate 2. However, when the second side surface S4 is formed in a planar shape, The four seal portions 34 are also formed in a planar shape.

Similar to the second seal portion 32, the fourth seal portion 34 is made of a dense material having a higher electrical resistivity than the first seal portion 31 and the third seal portion 33. Fourth seal portion 34 is, for example, crystallized glass, spinel _{oxides, MgO,} can be composed of _{Al 2 O 3, Y 2 O} 3 at least one selected from. Although the electrical resistivity of the 4th seal | sticker part 34 is not restrict | limited in particular, Like the 2nd seal | sticker part 32, it can be set to 10000 [ohmcm] or more and 1 * 10 < ¹² > [ohmcm] or less, 1 * 10 < ⁵ >. [Ωcm] or more is preferable, and 1 × 10 ⁶ [Ωcm] or more is more preferable.

(Manufacturing method of fuel cell 1)
Next, an example of a method for manufacturing the fuel cell 1 will be described.

  First, a molded body of the porous support substrate 2 having six gas flow paths 2a is formed by extruding a clay prepared by adding a pore former and a binder to the powder of the porous support substrate 2.

  Next, the material for the anode current collecting layer 41 is formed into a paste and printed on the shaped body of the porous support substrate 2, thereby forming the shaped body for the anode current collecting layer 41. Subsequently, the material for the anode active layer 42 is formed into a paste and printed on the body for the anode current collecting layer 41 to form a body for the anode active layer 42.

  Next, the material of the interconnector 8 is made into a paste and printed on the molded body of the fuel electrode current collecting layer 41 to form the molded body of the interconnector 8.

  Next, the material of the solid electrolyte layer 5 is made into a paste and printed on the molded body of the fuel electrode active layer 42 to form the molded body of the solid electrolyte layer 5. At this time, the paste of the material of the solid electrolyte 5 is printed on the first main surface S1 and the second main surface S2 of the porous support substrate 2, so that the first seal portion 31 and the third seal in the dense seal layer 30 are printed. The formed body of the portion 33 is manufactured integrally with the formed body of the solid electrolyte layer 5.

  Next, the molded body of the porous support substrate 2, the fuel electrode 4, the interconnector 8, the solid electrolyte layer 5, the first seal portion 31, and the third seal portion 33 is co-fired (1300 to 1600 ° C., 2 to 20 hours). .

  Next, the material of the second seal portion 32 of the dense seal layer 30 is made into a paste and printed on the first side surface S3 and the second side surface S4 of the porous support substrate 2, so that the second of the dense seal layer 30. The molded body of the seal part 32 and the fourth seal part 34 is produced. And the molded object of the dense seal layer 11 is baked (1300-1500 degreeC, 1 to 10 hours).

  Next, the air electrode 6 is formed into a paste and printed on the solid electrolyte layer 5, thereby forming a molded body of the air electrode 6. Subsequently, the material for the air electrode current collecting layer 7 is formed into a paste and printed on the formed object for the air electrode 6, thereby forming the formed object for the air electrode current collecting layer 7.

  Next, the molded object of the air electrode 6 and the air electrode current collection layer 7 is baked (900-1100 degreeC, 1 to 20 hours).

(Feature)
The dense seal layer 30 covering the porous support substrate 2 includes a first seal portion 31 disposed on the first main surface S1 and a second seal portion 32 disposed on the first side surface S3 and continuing to the first seal portion 31. Have. The electrical resistivity of the second seal part 32 is higher than the electrical resistivity of the first seal part 31.

  Thus, since the second seal portion 32 made of a material having a high electrical resistivity is disposed on the first side surface S3 of the porous support substrate 2, the dense seal layer 30 is made of the same material as the solid electrolyte layer 5. Compared with the case where the whole is comprised, it can suppress that an electric current flows into the back from the surface of the dense seal layer 30. FIG. Therefore, it is possible to suppress a weak leak current from flowing from the first power generation unit 10a toward the second power generation unit 10b or from the second power generation unit 10b toward the first power generation unit 10a.

(Modification)
As mentioned above, although embodiment of this invention was described, this invention is not limited to these, A various change is possible unless it deviates from the meaning of this invention.

  In the above-described embodiment, the case where the dense seal layer according to the present invention is applied to a solid oxide fuel cell has been described. However, the dense seal layer according to the present invention is not limited to a solid oxide fuel cell, but a solid oxide type. The present invention can be applied to a solid oxide electrochemical cell including an electrolytic cell.

  In the above embodiment, three first power generation units 10 a are arranged on the first main surface S <b> 1 of the porous support substrate 2, and three second power generation units 10 b are arranged on the second main surface S <b> 2 of the porous support substrate 2. However, the numbers of the first power generation unit 10a and the second power generation unit 10b can be changed as appropriate.

  In the above embodiment, the first seal portion 31 of the dense seal layer 30 is integrally formed of the same material as the solid electrolyte layer 5 of each first power generation unit 10a, but is different from the solid electrolyte layer 5. It may be formed separately depending on the material. Similarly, the third seal portion 33 of the dense seal layer 30 is integrally formed of the same material as that of the solid electrolyte layer 5 of each second power generation portion 10b, but is made of a material different from that of the solid electrolyte layer 5. It may be formed separately.

  In the above embodiment, the first seal portion 31 of the dense seal layer 30 covers the entire surface of the first main surface S1 of the porous support substrate 2, but may cover only a part of the first main surface S1. Good. In this case, the remaining portion of the first main surface S1 may be covered by extending at least one of the second seal portion 32 and the fourth seal portion 34, or a denseness different from that of the second seal portion 32 and the fourth seal portion 34. The remainder of the first main surface S1 may be covered with a quality material. Similarly, the third seal portion 33 of the dense seal layer 30 covers the entire surface of the second main surface S2 of the porous support substrate 2, but may cover only a part of the second main surface S2. In this case, the remainder of the second main surface S2 may be covered by extending at least one of the second seal portion 32 and the fourth seal portion 34, or may be different from the second seal portion 32 and the fourth seal portion 34. The remainder of the second main surface S2 may be covered with a quality material.

  In the above embodiment, the second seal portion 32 of the dense seal layer 30 covers the entire first side surface S3 of the porous support substrate 2, but may cover only a part of the first side surface S3. In this case, the remainder of the first side surface S3 may be covered by extending at least one of the first seal portion 31 and the third seal portion 33, or a dense material different from the first seal portion 31 and the third seal portion 33. You may cover the remainder of 1st side surface S3 with material. Similarly, the fourth seal portion 34 of the dense seal layer 30 covers the entire surface of the second side surface S4 of the porous support substrate 2, but may cover only a part of the second side surface S4. In this case, the remainder of the second side surface S4 may be covered by extending at least one of the first seal portion 31 and the third seal portion 33, or a dense material different from the first seal portion 31 and the third seal portion 33. You may cover the remainder of 2nd side S4 with material. Even in these cases, it is possible to suppress the flow of current from the front to the back of the dense seal layer 30, so that the first power generation unit 10a toward the second power generation unit 10b or the second power generation unit 10b to the second It is possible to suppress a weak leak current from flowing toward one power generation unit 10a.

  In the above embodiment, the configurations of the first power generation unit 10a and the second power generation unit 10b of the fuel cell 1 have been described with reference to FIG. 3, but the configurations of the first power generation unit 10a and the second power generation unit 10b are appropriately changed. Is possible. The 1st electric power generation part 10a and the 2nd electric power generation part 10b should just have the fuel electrode 4, the solid electrolyte layer 5, and the air electrode 6. FIG.

  In the above embodiment, the dense seal layer 30 has both the second seal portion 32 and the fourth seal portion 34, but may have only one of them. Even in this case, current can be prevented from flowing from the front to the back of the dense seal layer 30. For example, when the dense seal layer 30 does not have the second seal portion 32, at least one of the first seal portion 31 and the third seal portion 33 may be extended to cover the second side surface S4.

2 porous support substrate S1 1st main surface S2 2nd main surface S3 1st side surface S4 2nd side surface 10a 1st power generation part 10b 2nd power generation part 30 Dense seal layer 31 1st seal part 32 2nd seal part 33 3rd seal Part 34 fourth seal part

Claims (4)

An insulating porous support substrate having a first main surface, a second main surface, a first side surface and a second side surface;
A first power generation unit disposed on the first main surface of the porous support substrate;
A second power generation unit disposed on the second main surface of the porous support substrate;
A dense seal layer covering the porous support substrate;
With
The dense seal layer includes a first seal portion that covers the first main surface, and a second seal portion that covers at least a part of the first side surface and continues without overlapping the first seal portion,
The first seal portion is made of a material having oxide ion conductivity higher than electron conductivity,
The second seal portion is made of a material different from the material of the support substrate,
The electrical resistivity of the second seal part is higher than the electrical resistivity of the first seal part,
Electrochemical cell. The second seal part is composed of at least one selected from crystallized glass or spinel oxide, MgO, Al ₂ O ₃ , and Y ₂ O ₃ .
The electrochemical cell according to claim 1. The second seal portion covers the entire first side surface;
The electrochemical cell according to claim 1 or 2. The dense seal layer includes a third seal portion that covers the second main surface, and a fourth seal portion that covers at least a part of the second side surface and continues without overlapping the third seal portion,
The fourth seal portion is made of a material different from the material of the support substrate,
The electrical resistivity of the fourth seal part is higher than the electrical resistivity of the third seal part,
The electrochemical cell according to any one of claims 1 to 3.